Method and device for regulating the moisture content of endless moving webs of fibrous material



Aug. 30 1960 P. R. LIPPKE 2,951,007

METHOD AND DEVICE FOR REGULATING THE MOISTURE CONTENT OF ENDLESS MOVINGWEBS OF FIBROUS MATERIAL Filed .June e, 1957 2 sheets-sheet 1- PAuL e.UPP/ 5 @WJ www l ATTORIJEKSA Aug. 30, 1960 P. R. LIPPKE 2,951,007 METHODAND 'DEVICE FOR REGULATING THE MOISTURE CONTENT oF ENDLEss MOVING wEBsorFrBRous MATERIAL Filed June 6. 1957 2 Sheets-Sheet 2 INVENTOR FIBEROUSMATER-IAL FEED E m w L e. w. m

ATTORNEYS United tates Paul R. Lippke, R0. Box 163, Augustastrasse 17,Neuwied-Rhine, Germany Filed June 6, 1957, Ser. No. 664,058

14 Claims. (Cl. 162-198) The present invention is to improve thepossibilities of equalizing the moisture content in endless moving websof fibrous material. Y

It is known that such endless webs, as e.g. of paper, pulp or board havenot only considerable variations in moisture content in direction of therunning web but also across the entire web. These variations partlyresult from irregularities in the sheet formation being unavoidable onthe wire and partly from the fact that the presses and the felts do notwork equally and but not least from irregularities within the dryingprocess in so far as the pressure of steam, which is used for the dryingprocess, or the drying ability of the paper, changes. These variationsof the moisture content disturb the manufacture of the webs to a highdegree, since they prevent an otherwise given possibility, namely toeXsiccate the water only to such a degree that the ready dried web is inhygroscopic balance with the surrounding air in the iinishing room.

The possibilities of modern techniques to improve moisture content ofsuch webs can be realized by the following methods. Firstly bycontrolling the basis weight of the web, either at the wet part of thedrying machine or at the dry end of the machine and that by means ofvarying the supply or consistency of feed in order to equalize the web.Secondly it is possible to measure the moisture content kat the end ofthe drying section. According to this measurement a regulator isinuenced which in turn controls the flow of steam to the dryers.Furthermore it has been proposed to utilize the measuring value of themoisture meter for the adjustment of the moistening device so thatcorresponding with the moisture content 4of the paper more or less wateris added tothe paper web. 'The measuring instruments suitable fortesting both vbasis weight and moisture content are ot differentconstruction. For the regulating purposes, too, various procedures areknown.

-All these measuring instruments and regulators incorporate lonedisadvantage which consists in the fact Ythat it is indeed possible toequalize the moisture content in the running direction of the webcorresponding to the received measuring value from a certain place ofthe web but 'not to equalize the variations of the moisture contentacross the web which is far more disadvantageous in impairing theeconomic production.

This limitation of the presently known regulating procedures for themoisture content of such webs results in applying the disadvantageousmanufacturing method that the entire Web has to be dried down to a verylow moistuie content, generally 2-3% H2O, in order 'to be sure -thatalso the spots which have remained thicker in-the formation process orin the mechanical purification of the web and which are accordinglymoisture will dry suiciently. This low moisture content then is keptcon- Stant Vby such a regulating procedure. Since it is not possible todeliver the paper with such a low -moisture 'content wateris sprayed onthe web subsequently.

VForthis purpose spray devices of various construction are applied. Itis evident that this procedure is a very uneconomical one. Thehygroscopic balance of diiierent paper types at a climate of 65%relative humidity is about between 7 to 11% H2O. If the paper web hasbeen dried down to 2-3% H2O or sometimes to even a smaller degree it isabsolutely necessary to add consider-able amounts of water to the paper.This procedure causes an alteration of the surface of the paper and isvery disadvantageous. Moreover in many cases it is not possible to carryout such an intensive moistening of the paper.

The present invention takes care of all these disadvantages and startsfrom the principle that an over-drying of the paper and the connectedhorniiication of the fibre must be avoided as well as the excessiveconsumption of steam and the slow-down of the paper machine speed. Atthe same time the invention takes care of a far-reaching equalization ofthe moisture content of the paper being Astill in the drying pro-cessand furthermore allows a subsequent correction of the moisture contentof the paper web, as well in the running direction as across the web bysubsequent correction of the irregularities which unavoidably remainafter the forming and drying of the web.

By means of this invention it is also possible to eliminate thevariations of the basis weight which up to now unavoidable in the stageof forming the web and to remove thereby the already describedditiiculties in the later converting process of the paper.

The investigations being performed on occasion of this invention haveshown that the peaks and irregularities alongV and across the paper web,which are of disadvantageous influence to an economic drying,exclusively result from variations of the basis weight, with theunderstanding that the steam for the drying process is suppliedconstantly. According to this invention the irregularities of theiibrous web shall be eliminated by the following procedure: by theperiodic movement of the measuring feeler of a moisture meter which isto be installed at or behind the dry end of the paper machine, themoisture content of every part of the web which corresponds with thebreadth of the measuring feeler, is measured. In relation to thesemeasuring values a plurality of partial elements of the fibrous materialinlet slit is adjusted by means of a continuous regulating device, whichwill be described later on. Just so Ia plurality of partial elements ofa spray device are adjusted, also in a manner, which will be describedlater on. By these procedures rstly .the basis weight variations-will beeliminated and secondly, by means of a more or less intensivemoistening, the remaining variations ofthe moisture content will beequalized so that a paper of most equal basis weight and moisturecontent will be obtained inally. The invention eX- tends tothe'application of the therein described procedure and to theperformance of the equipment being necessary for the execution of theproced-ure.

In order to illustrate the performance of the invention an `example isrepresented. Fig. 1 shows a moisture prole of `a paper web underdiierent drying conditions. Fig. 2 illustrates in a total scheme thearrangement of the single parts at a paper -machine and the constructionof the regulator. Fig. 3 represents in a scheme the arrangement of thewater spray nozzles with air pressure diffusion. Fig. 4 shows an exampleof the performance of the adjusting device for the variation of the owinlet. Fig. 5 shows the example of an adjusting device for the partialalteration of the eiectiveness of [a brush-or spray damper for themoistening of the paper web. Y

The execution of the invention is described v,in the following example:

The moisturemeterlwhichtraverses the web period- .,ieally is arranged atthe end of the drying-section. The

measuring values are recorded on the recording strip 2, whereat therecording strip is only moving when the measuring feeler of the-moisture meter from the front Iside' Vto the driving sideiwhilst theVtransport ofthe recording strip is stopped during the returnmovement.This is necessary in order to have the possibility to compare therecording diagrams right next t-o each other. The Vmeasuring value ofthe moisture meter is fed' at the same time to the regulator 3 which maywork in any way. The steering mechanism of the regulator, in thisexample an'electromotor 4, acts the arm 5 which inuences by means of thegroove, which is formed by the two control surfaces 6,`via the roll 7the needle valve 8.

i Imagine the arm 5 being pushed forward so far that the Vroll 7 isplaced between the control surfaces 6 it becomes Yevident that theneedle valve 8 will beopened more for the case in which the moisturemeter inds out a lower moisture content or less if a spot of highermoisture content has been tested. A spray nozzle of the moistening'apparatus 9 whichbelongs to this needle valve accordingly would addmore or less water to the paper. The regulator 3 has a desired valueadjustment 10 by means of -which the nominal value of the moisturecontent of the paper web can be xed. The difference value between themoisture meter 1 and the desired value adjustment 10Yeffects theregulatingprocess and by means of the needle valve the amount of wateris sprayed on the place concerned of the web. This amount of water andthe already existing moisture content in the web yield together thedesired value.

Therewith the function of the regulating process would be described forthe single nozzle. But since it is necessary, to alter the eiciencycontinuously not only from one nozzle, but from a plurality of nozzlesand since it would be uneconomical to provide a plurality of suchregulators, the arm 5 being the actual steering mechanism is passedalong the needles which belong to the nozzles concerned, synchronizedwith the movement of the measuring feeler across the web, so that thosenozzles are `actuated which lie at the same place of the breadth of thepaper web where the measuring feeler stays.

It is possible to arrange all needle valves in one line and to move thearm 5 by means of the motor straight alongside these needle valves. Butit is even more advantageous to arrange all the needle valves in acircle 'round the swivel axle of thearm 5 and to turn the arm, which isxed on the drive shaft, corresponding with the movement of the measuringfeeler to and fro. Now the purpose of the control surfaces 6 is to beunderstood from the following. They are so dimensioned that they have atthe beginning a distance which corresponds to the entire regulating liftof the valve rod and having a distance at the middle, which correspondsexactly with the diame- Ater ofthe roll 7.

Arm 5 together with the control surfaces l6 can now oc cupy anotherposition opposite to the rolls 7 of the various nozzles for everysituation in the rotating movement being equivalent to the position ofthe measuring feeler on the web, and the adjustment of the needle valveswill be altered according to the actual moisture reading of the moisturemeter. It is planned to install a spray damper for water at which thenecessary air atomizer-nozzles 12 are arranged, as shown in Figure 3,together on a pipe in such a distance of the web that their cones ofdispersion Ymeet exactly on the surface of the sheet. In order to keepthe cones of dispersion and the output of the nozzles constant, air witha constant pressure is fed to the common main pipe. Then the output ofeach nozzle is a1- tered by the respective needle valve 8. Thereby itcan be achieved that for every amount of Water which is to be atomizedyan absolutely equal dilfusion and a kconstant cone of dispersion can beguaranteed.

Withthe same arrangement it will be possible toicontrol thertibrouslmaterial feed inlet, too. Since the hydraulical resistance of theatomized nozzleis of av constant value and since the water pressure isconstant in front of the needle valves S it can be understood that apressure change will take place in the pipes behind the needle valves 8,which corresponds to the amount of water which is fed to every nozzle.This pressure change is used at the same time for an'alteration of thepassage cross section of the brous material feed inlet device. Theperformance of the necessary equipment is shown under Figure 4. The lip14 of the fibrous material feed inlet must, as already described before,be changed according to the measuring values of the moisture meter.'I'his is to be done as usual by means of the spindle 15 with thehandwheel 16.

The nut of the handwheel 16 is firmly imbedded. In order to obtain aself-acting control of the passage cross section of the fibrous materialfeed inlet the nut of the handwheel 16 is imbedded in the turnable leverarm 17 'which influences via the pressure cylinder 18 with its piston 19and counterspring 20 the position ofthe lip 14 of the fibrous materialfeed inlet.

In relation to every nozzle ofthe spray damper at the same place on therespective lip of the fibrous material feed inlet such a pressurecylinder is arranged. Both parts are connectedV by the common water pipeline. Every variation in this pipe line, which iscaused by the needlevalve 8 thus effects at the same time achange of the moistening as wellas a change-of the position ofthe fibrous material feed inlet lip 14.Consequently, the partial variations of the basis weight and the unevenmoisture content of the web resulting therefrom will be eliminated atthe same time. 1

Indeed, it is possible to realize the one and the other regulatingprocedure, eg. the control of the moistening and fibrous material feedinlet, either operating together or separately.

The moistening procedure by means of atomizernozzles for water,especially such nozzles, which operate with compressed air, will be inany case the most advantageous because of its possibility to limit theeffect of the moistening exactly; but it will be also possible tocontrol other sorts of moistening apparatuses in their efficiency acrossthe web.

In Fig. 5 such a possibility is illustrated. The needle valves 8 areconnected with the pressure cylinders 21 which are distributed along theentire breadth of the brush damper in the same number as lips are at thefibrous material feed inlet. If an arbitrary leak is fed into theconnecting line between the needle valve 8 and the respective pressurecylinder 21, there willunder the supposition of constant water pressurein front' of the needle'valve and constant amount of water in front ofthe leak-occur a corresponding pressure which corresponds to thedifference between the actual moisture content-which is represented bythe moisture meter--and the desired value, which has been adjusted atthe regulator. This Ypressure causes by means of the piston 22 and thecounter spring a corresponding variation of the position of theimpinging plate 24.

At a great diiference between the two moisture values the impingingplate is pushed towards the bristles of the brush so that more Watersprays on the web. Whilst at a smaller difference between the twomoisture values the impinging plate is not pushed so far towards thebrush and less water is sprayed on the web.

When using atomizer nozzles working withV an impinging plate the sameVdevice can be applied. The water spray which streams out of the nozzle25 can be atomized by means of the impinging plate more or less, themoistening of the Vweb being in this case also dependent on thedifference-,value between moisture reading of the moisture meter andadjustment of the desired value at the regulator.

Since thetwo Ylast-mentioned moistening procedures do not olfer theexactness which is necessary for a useful moisteningA and thedistribution of the'water to single sections of the Web these proceduresshall be mentioned only in order to complete the description on thepossibilities of the application of the invention. Naturally, it will bepossible to connect the control of the moistening device with that ofthe fibrous material feed inlet when applicating such a moisteningdevice, too, and t produce the same effect as under application of amoistening by means of air-pressure atomizing.

It has been explained in the present description of the application andthe idea of the invention that it is not only possible to obtain bymeans of this invention a subsequent moistening which treats the singleparts of the paper Vweb differently but furthermore to bring about thatthe excessive drying of single parts of the web will be avoided.

In this case, the moistening apparatus, preferably a device with airpressure atomizer nozzles, is installedas shown in Fig. Z-Within thedrying section, and that at a place, where the paper web is not yet sofar overdried that hornication takes place at the surface.

As already described, more water is added now to the drier parts of thepaper so that the paper becomes moister.

By the increased evaporation power Which becomes necessary at this placeof the web the surface temperature of the following drying cylinders isreduced to the actual measure of the other parts of the cylindersurface.

The entire arrangements can remain the same as described.

I claim:

1. The method of making a web of material and regulating the liquidcontent and basis weight thereof which comprises forming a liquid slurryof the material into a sheet by passing slurry thereof through anelongated slit, passing the sheet along an elongated course, evaporatingliquid from the sheet as it traverses said course, successively sensingliquid content of the web at points disposed along a path extendingacross said course and depending upon the amount of liquid sensed atsaid points simultaneously applying liquid in varying amounts across thewidth of the web and varying opening size along said slit to improveuniformity of the web with respect to liquid content and basis weight,the slit opening and amount of liquid applied when a liquid deficiencyis sensed, each simultaneously being increased at corresponding pointsalong the slit and across the web, respectively and when a liquid excessis sensed each simultaneously being decreased at corresponding pointsalong the slit and across the web, respectively, to realize saidimproved uniformity.

2. The method of regulating the liquid content of a Web of materialwhich comprises passing the web along an elongated course, evaporatingliquid from the web as it traverses said course, successively sensingliquid content of the web at points disposed along a path extendingacross said course, and depending upon the amount of liquid sensed atsaid points, applying liquid in varying amounts across the width of theweb to improve uniformity of the web with respect to moisture content.

3. The method of making a web of material and regulating the basisweight thereof which comprises forming a liquid slurry of the materialinto a sheet by passing slurry through an elongated slit, passing thesheet along an elongated course, successively sensing liquid content ofthe web at points disposed along a path extending across said course,and depending upon the amount of liquid sensed at said points, varyingopening size along said slit to improve uniformity of the web withrespect to the basis weight thereof.

4. Apparatus for making a web of material and regulating the liquidcontent and basis weight thereof, which comprises means for forming aliquid slurry of the material into a sheet by passing slurry through anelongated slit, means for passing the sheet along an elongated course,means for evaporating liquid from the .sheet as it traverses saidcourse, sensing means for successively sensing liquid content of the webat points disposed along a path extending across said course, lirst andsecond lreactive" rnens responsive to the sensing means depending on theamount of liquid sensed by the sensing means, the first reactive meansbeing for applying liquid in varying amounts across the width of the weband the second reactive means being for varying opening size along saidslit, said first and second reactive means being effective tov improveuniformity of the web with respect to moisture content and basis weight.

5. Apparatus according to claim 4, the first reactive means comprising aplurality of valved liquid lines disposed at spaced intervalstransversely of the Web course for discharge of liquid to the web, thesensing means comprising a liquid meter for sensing liquid of the web,means for moving the liquid meter back and forth across the web,transmitter means operatively connected to the liquid meter, and valvecontrol means responsive to the transmitter means arid effective tocontrol the valves of said valved liquid lines, the transmitter meansbeing effective to actuate the said valves for valve response to travelof the liquid meter in one direction only across said web, the secondreactive means comprising a plurality of slit opening size changingmeans for controlling the slit opening size at places along the slit andslit control means for the slit opening size changing means foractuating said changing means, said slit control means being arrangedfor response to pressure drop associated with the said valved liquidline. c

6. Apparatus according to claim 5, said valved liquid lines beingprovided with atomizer discharge nozzles, the atomizer nozzles beingconnected to a constant pressure compressed air source, wherebycompressed air can be discharged with liquid to provide improved liquiddistribution to the web.

7. Apparatus according to claim 6, said valve control means comprising acontrol surface, the valve in each valved line having means forcooperation with said control surface and operating the valve, and meansfor moving the control surface so that it operatively engages aplurality of the means for cooperating with the valve control surface.

8. Apparatus according to claim 5, each valved line having a dischargenozzle, an impingement baffle Ifor each valved liquid line disposedadjacent the line nozzle discharge, baffle positioning means for eachbaille whereby the baffle can be positioned relative to its nozzle anddelivery of liquid to the web can thereby be controlled, each bafflepositioning means comprising a spring biased pistoncylinder arrangement,conduit means for communicating the piston-cylinder arrangement withpressure in front of its valve and a leak in said conduit means wherebyactuation of a valve causes a pressure change in the Valves conduitmeans and actuates the valves piston-cylinder arrangement and in turnthe valves impingement baffle.

9. Apparatus for making a web of material and regulating the liquidcontent thereof, which comprises means for passing the web along anelongated course, means for evaporating liquid from the web as ittraverses said course, sensing means for successively sensing liquidcontent of the Web at points disposed along a path extending across saidcourse, reactive means responsive to the sensing means depending on theamount of liquid sensed by the sensing means, the reactive means beingfor applying liquid in varying amounts across the width of the web, saidreactive means being effective to improve uniformity of the web withrespect to moisture content.

10. Apparatus according to claim 9, the reactive means comprising aplurality of valved liquid lines disposed at spaced intervalstransversely of the web course for discharge of liquid into the web, thesensing means cornprising a liquid meter for sensing liquid of the web,means for moving the liquid meter back and forth across the web,transmitter means operatively connected to the liquid meter, and valvecontrol means responsive to the transmitter means and effective tocontrol the valves of Vsaid valved liquid lines', the transmittermeansbeing Veiective to actuate the said valves for valve response totravel of the liquid meter in one direction only across said Web.4

11. Apparatus according to claim 9, said valved liquid lines beingprovided with atomizer discharge nozzles, the atomizer nozzles beingconnected to a constant pressure compressed air source, wherebycompressed air can be discharged with liquid to provide improved liquiddisltribution to the web.

12. Apparatus according to claim 9, said valve control means comprisinga control surface, -the valve in each valved line having means forcooperation with said control surface and operating the valve, and meansfor moving the control surface so that it operatively engages aplurality of the means for cooperating with the valve control surface.

13.v Apparatus according -to claim 9, each valve line having a dischargenozzle, and impingement bame for each valved liquid line disposedadjacent the line nozzle discharge, baie positioning means for eachbaille where- Vby the baffle can be positioned relative to its nozzleand delivery of liquid to the web can thereby be controlled, each bafepositioning means comprising aspring biased "piston-cylinderarrangement, conduit means for communicating the piston-cylinderarrangement with pressure in front of its valve and a leak in saidconduit means whereby actuation of a valve causes apressure change inthe valves conduit means and actuates the valves piston- Acylinderarrangement andAinmturnthe valves impinge ment baille, Y Y

14. Apparatus for making a web of material and regu- -lating thebasisweight thereof, which comprises means for forming a liquid slurry of thematerial into a sheet by passing slurry through fan elongated slit,means for pass- Vving the sheet along an elongated course, sensing meansfor successively sensing liquid content of the web at points disposedalong a path extending across said course, reactive means responsive tothe sensing means depending on the amount of liquid sensed by thesensing means, the reactive means being for varying opening size alongsaid slit, said reactive means being effective to improve uniformityofthe web with respect to basis weight.

References Cited in the le of this patent UNITED STATES PATENTS 423,435Great Britain J an. 28,

1. THE METHOD OF MAKING A WEB OF MATERIAL AND REGULATING THE LIQUIDCONTENT AND BASIS WEIGHT THEREOF WHICH COMPRISES FORMING A LIQUID SLURRYOF THE MATERIAL INTO A SHEET BY PASSING SLURRY THEREOF THROUGH ANELONGATED SLIT, PASSING THE SHEET ALONG AN ELONGATED COURSE, EVAPORATINGLIQUID FROM THE SHEET AS IT TRAVERSES SAID COURSE, SUCCESSIVELY SENSINGLIQUID CONTENT OF THE WEB AT POINTS DISPOSED ALONG A PATH EXTENDINGACROSS SAID COURSE AND DEPENDING UPON THE AMOUNT OF LIQUID SENSED ATSAID POINTS SIMULTANEOUSLY APPLYING LIQUID IN VARYING AMOUNTS ACROSS THEWIDTH OF THE WEB AND VARYING OPENING SIZE ALONG SAID SLIT TO IMPROVEUNIFORMITY OF THE WEB WITH RESPECT TO LIQUID CONTENT AND BASIS WEIGHT,THE SLIT OPENING AND AMOUNT OF LIQUID APPLIED WHEN A LIQUID DEFICIENCYIS SENSED, EACH SIMULTANEOUSLY BEING INCREASED AT CORRESPONDING POINTSALONG THE SLIT AND ACROSS THE WEB, RESPECTIVELY AND WHEN A LIQUID EXCESSIS SENSED EACH SIMULTANEOUSLY BEING DECREASED AT CORRESPONDING POINTSALONG THE SLIT AND ACROSS THE WEB, RESPECTIVELY, TO REALIZE SAIDIMPROVED UNIFORMITY.